This program project will require the procurement and processing of a large bulk of histopathologic materials. These materials need to be processed, not only for routine histopathologic diagnosis of the tumor and premalignant lesions, but also for the various immunohistochemical and in situ hybridization studies proposed in the basic research projects. Preparation of tissue samples for these studies cannot be processed by a regular pathology laboratory since they require special care in their handling. For example, to obtain optimum results with mRNA in situ hybridization, all glassware should be baked, and tissue sections need to be handled with special care to avoid RNAase contamination. This Histology Laboratory Core will respond to such a special need and will prepare and distribute adequate tissue samples for the studies proposed in Projects 4 through 6. It will also function as a liaison with the Department of Pathology to coordinate the handling of pathology slides and paraffin blocks sent from collaborating institutions (e.g.,RTOG and CCOP institutions for Project 1). In addition, this core will process the immunohistochemical staining for the conduct of Project 3. Another major function of the laboratory will be the procurement and storage of both normal and malignant tumor samples for future use. This Core facility will become increasingly important since the proposed studies may find new molecular biologic of biochemical markers of interest that would warrant re-examination of some samples in the future.